This invention relates to a method of using selected photoactive compounds with acid hardening resins to produce thermally stable, submicron images using near ultraviolet radiation.
Workers in the field of photolithography desire photoresists capable of producing images with submicron resolution. My prior application Ser. No. 616,518 is directed to a dual acting aqueous developable polymer coating composition containing an acid hardening resin system and a photoacid generator which produces carboxylic acid upon exposure to actinic radiation such as, for example near ultraviolet radiation, leading to images having a resolution as low as about 0.7 microns. My prior application Ser. No. 818,430 disclosed an acid hardening negative acting photoresist composition capable of producing even higher resolution, down to about 100 nanometers, utilizing short wavelength actinic radiation such as, for example; deep ultraviolet, x-ray and electron beam radiation. The halogen-containing photoacid generators used in that invention are useful with short wavelength radiations but do not produce sufficient acid upon exposure to near ultraviolet radiation to catalyze the crosslinking of the acid hardening photoresist. Accordingly, the photoresists containing these photoacid generators can not be employed for use with near ultraviolet radiation to produce submicron images.
Recently a number of photolithographic imaging equipment manufacturers have announced advances in lenses and imaging systems capable of focusing near ultraviolet radiation to submicron dimensions.
Since conventional near ultraviolet photoresists are not capable of providing thermally stable high resolution submicron images (U.S. Pat. Nos. 3,692,560; 3,697,274; 3,890,152; and 4,404,272), these photoresists cannot be utilized with such advanced lenses and imaging systems to produce thermally stable, submicron images.
U.S. Pat. No. 3,042,51 5 discloses printout compositions which produce a color change upon exposure to ultraviolet light. The composition contains one or more aryl amines and one or more halogenated compounds. The use of diphenylamine, triphenylamine and N-phenyl-1-naphthyl-amine along with iodoform, carbon tetrachloride and carbon tetrabromide is disclosed.
U.S. Pat. No. 4,634,657 discloses photoimaging compositions which produce improved color comprising substituted 1,2-dibromoethane compounds, a leuco dye, optional monomeric compound and a photoinitiator. Among extensive lists of useful leuco dyes, aminophenothiazine and aminophenoxazine are included. There is no teaching or suggestion in this disclosure of the production of photoresists.